# Gravitational attraction of two objects

• mrroboto187
In summary, the conversation discusses a problem involving two spherical objects with a combined mass of 150kg and a gravitational attraction of 8.00X10^-6 N when their centers are 20 cm apart. The participants suggest using Newton's law of universal gravitation and solving a quadratic equation to find the individual masses of the objects.
mrroboto187
okay so this is my first time posting anything here so forgive me if I've done something wrong (and do let me know). but I've been struggling with this problem now for a couple days and it seems like the answer is on the tip of my tongue but i can't come up with the steps. so if anyone could give me a clue, that would be great. here goes:
Two spherical objects have a combined mass of 150kg. The gravitational attraction between them is 8.00X10^-6 N when their centers are 20 cm apart. What is the mass of each?
I'm sure I'm missing something really simple so any help is appreciated.
thanks.

Try writing down Newton's law of universal gravitation. That gives you a relation between m1 and m2. The fact that they sum to 150kg gives you a second relation. You should be able to solve it from there.

the part i don't get is the relation between the sums. i know
(G*M1*M2)/r^2=F of m1 on m2,
and I've been thinking about this for a while now and it's driving me crazy. i can't find a relation between the sum and the product.

Put m1 = 150 - m2 into your equation above and solve the quadratic for m2.

If quadratic is too anoying you could do algebra to isolate the varible, that's what I've always done.

awesome, i feel really dumb now. thanks a bunch though.

I don't think you can get around solving a quadratic..

use a calculator. obviously technology is no substitution for knowing how to solve it with pencil and paper. but a calculator will do it, and fast mind you.

marcusl said:
I don't think you can get around solving a quadratic..

I just looked at it quick, you may be right. I've just never run across a problem in my physics class in which you can't isolate one variable.

## 1. What is gravitational attraction?

Gravitational attraction is the force of attraction between two objects due to their mass. The larger the mass of the objects, the stronger the gravitational attraction between them.

## 2. How is the strength of gravitational attraction calculated?

The strength of gravitational attraction between two objects is calculated using the universal law of gravitation, which states that the force of attraction is directly proportional to the product of the masses of the objects and inversely proportional to the square of the distance between them.

## 3. What is the difference between gravitational attraction and gravitational force?

Gravitational attraction refers to the force of attraction between two objects, while gravitational force refers to the actual force acting on the objects due to their gravitational attraction. Gravitational force is a vector quantity, meaning it has both magnitude and direction, while gravitational attraction is a scalar quantity, meaning it only has magnitude.

## 4. How does distance affect gravitational attraction?

The strength of gravitational attraction between two objects decreases as the distance between them increases. This relationship is described by the inverse square law, meaning that if the distance between two objects is doubled, the strength of gravitational attraction decreases by a factor of four.

## 5. Can gravitational attraction be shielded or cancelled out?

While it is not possible to completely shield or cancel out gravitational attraction, there are other forces, such as electromagnetic forces, that can counteract its effects. For example, a rocket is able to escape the Earth's gravitational pull by using powerful engines to generate enough thrust to overcome the force of gravity.

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